[BrendaEM]

I most-likely will buy all carbide bits, and it would be good to know which are better in small mills?

If you were buying bits over again, would you buy 2 or 4 flute bits?

Can most 4-flute centercutting bits really centercut?

Are 2 flute bits as strong, and can they make just as nice surface finish in various materials? Is cutting speed the only advantage for 4-flute bits?

Are the dedicated aluminum-only bits necessary for non-production aluminum milling? Or, could I make do with one set of carbide bits, if I watch the speed and feedrate, and coolant/lubrication?

I've seen a few 3-flute bits; wouldn't this be the answer, if they made more?

I appreciate all your help, for yet another newbie question.

[I have been seeing inconsistency with this issue. Makers claim one thing. I've seem examples otherwise. I think that only the modern machining books would include information on carbide bits.]

[Mcgyver]

cutting speed has nothing do to with # flutes, # of flutes affects the feed rate - feed based on chip load per tooth. cutting speed is a surface speed, ie fee per minute and is determine by dia and rpm's

re AL bits, they have a different helix - if you are maxing out industrial cutting ok but regular bits work fine and you do not need a set of AL tooling in the homeshop.

i prefer 4 flute for general work, its not so wump wump wump and produces a nicer finish. 2 flutes are for plunging or for slots and have their place. this is mostly based experience with hss ... i wouldn't think it would be any different with carbide, the principle is the same. btw, why the predisposition to carbide? what are you machining? there are lots of reasons why one might go carbide but as a self proclaimed newbie I'm wondering if weighed all the pros and cons? great for industry where time=$$$ but for the home shop its more expensive tooling, easier to break and most home shop equipment does come close to making use of its higher removal rate capabilities. just a thought.

[philbur]

What material and type of work are you going to be cutting.

The biggest cost with end mills is the inability to re-sharpen them.

2 flutes are for slots or where you need space for the chips to clear, such as a blind pocket. 4 flutes will let you run at twice the feed of a 2 flute for the same surface finish, if your mill is up to it, and are best for profiling.

Carbide can cost as much as 3 times HSS but can last three times as long, providing you know what you are doing. If you don't they can last half as long, small diameters break very easily. Learn with HSS.

End mills are short life consumables, particularly with CNC, so don't worry to much just buy some and practice. Don't form a lifetime bond with them, it will end in tears.

Regards
Phil

I most-likely will buy all carbide bits, and it would be good to know which are better in small mills?

If you were buying bits over again, would you buy 2 or 4 flute bits?

Can most 4-flute centercutting bits really centercut?

Are 2 flute bits as strong, and can they make just as nice surface finish in various materials? Is cutting speed the only advantage for 4-flute bits?

Are the dedicated aluminum-only bits necessary for non-production aluminum milling? Or, could I make do with one set of carbide bits, if I watch the speed and feedrate, and coolant/lubrication?

I've seen a few 3-flute bits; wouldn't this be the answer, if they made more?

I appreciate all your help, for yet another newbie question.

[I have been seeing inconsistency with this issue. Makers claim one thing. I've seem examples otherwise. I think that only the modern machining books would include information on carbide bits.]

[in2steam]

Phil says it best, as I stated in my other post I unwittingly tried to use carbide on a larger lathe(upside down and then sideways untill corrected by a rather mad insructor) and got really mixed results but it did work. Carbide is fickle you cannot esp when done manually always get the same results. It needs to work alot harder then HSS and in some cases you need to be very acurate on your last pass or the next will be well less then par. HSS bits are cheap, and easily replaced and sharpened(with the proper equipment) carbide esp cemented and solid carbide is niether(you need diamond or cbn).
Inserts are nice, but you still have to change them and set them.

In regards to your other post you can also buy regular HSS flycutter which do work fairly well, esp in alum and softer materials. I would buy cheaper single fly cutter and buy both HSS, and cemented carbide tips and compare and contrast them, you might be suprised at the difference. You can buy from several suppliers pre sharpened HSS tooling sets as well which gives you a good reference when you need to regrind yours. Then all you need is a regular old grinding wheel, nothing special.
HSS is often nice for that little clean up you need to do, carbide I have found not as easy to do that with-but then again I do alot of maintenance work very little production.

I would buy the 40-60 dollar set of HSS endmills and a collet set to match or holders I suppose if you prefer. THese all pretty much come with 2 and 4 flute, I find, and this entirely on a manual machine, that 2 flutes do better on a AL, brass, and plastics as they give more chip clearance. You can take a little larger cutting with these so it makes your work a touch easier. GI and all steels I use 4 flutes, unless slotting or other special work. You need to make sure that you can plunge mill with the set you buy also as that is another problem.


chris

[BrendaEM]

"Why the predisposition to carbide?"

It was my hope that the factory ground edge on carbide would wear longer than HSS. I know that HSS could be resharpened, but for some time, I am going to lack the the equipment and skill to do sharpen an endmill, so I need the bit at least to be true and sharp--even if I cannot be.

"what are you machining?" Largely, mild steel, aluminum, and hard plastic.

I have several projects planned. I am going to be making some motorcycle/bicycle type drop-out parts. I don't know whether or not I'll go with steel or aluminum. I am going to make some front vehicle suspension type parts, They will be steel.

I have some other little projects I want to make, some optic holders: mirror and beam splitter holders, who knows maybe even a spatial filter. I may be tempted to lighten my bike a bit, which may have anodize on parts. Lastly, I may help a friend make a boat-accessory from stainless, but I know whatever good bit I use for for, won't be good for long. I need to look into some kind of coolant situation.

I had planned to get just a few sizes or endmills say, 1/8", 1/4", and 1/2" in carbide, but perhaps I should get a set of TiN HSS too, if not for in-between sizes, but for practice. The TiN might be slicker than the carbide for aluminum.

[Mcgyver]

It was my hope that the factory ground edge on carbide would wear longer than HSS. I know that HSS could be resharpened, but for some time, I am going to lack the the equipment and skill to do sharpen an endmill, so I need the bit at least to be true and sharp--even if I cannot be.

it think it will wear longer (if you don't chip it first ) either can be resharpened but the equipment isn't usually found in the beginners workshop...that of course can change over time

the tool life discussion is dependent on objectives - I'd argue in favour of carbide tooling in a commercial environment because i understand management accounting....contribution can increased even if at lower margins. problem is in the home shop all you really care about is $/cubic inch of removal. While carbide is a better performer in almost every sense (lasts longer, will cut tougher stuff, higher removal rates etc) when the machine's limitations (light bench mill) are considered I'd bet hss gives a better $/cubic inch removal rate.

Another consideration as that carbide is brittle, the included angle of the tool edge is not as acute as with hss...this results in a greater cutting force being required. handling greater cutting forces are obviously not what bench top mills are best at.

if you really want your tooling to last longer, slow everything down and cut with a decent chip load. tool life is not linear to cutting speed and goes up quickly as ideal speeds are exceeded

your call what you buy, I just think a lot of peeps newer to it pick carbide tooling for the wrong reasons; its as if because its more expensive and has higher performance specs they assume its 'just better' this is an oversimplification and is an erroneous mix of commercial and homeshop economics imo. buy one or two of each and do some experiments?

[in2steam]

"Why the predisposition to carbide?"

It was my hope that the factory ground edge on carbide would wear longer than HSS. I know that HSS could be resharpened, but for some time, I am going to lack the the equipment and skill to do sharpen an endmill, so I need the bit at least to be true and sharp--even if I cannot be.

"what are you machining?" Largely, mild steel, aluminum, and hard plastic.

I have several projects planned. I am going to be making some motorcycle/bicycle type drop-out parts. I don't know whether or not I'll go with steel or aluminum. I am going to make some front vehicle suspension type parts, They will be steel.

I have some other little projects I want to make, some optic holders: mirror and beam splitter holders, who knows maybe even a spatial filter. I may be tempted to lighten my bike a bit, which may have anodize on parts. Lastly, I may help a friend make a boat-accessory from stainless, but I know whatever good bit I use for for, won't be good for long. I need to look into some kind of coolant situation.

I had planned to get just a few sizes or endmills say, 1/8", 1/4", and 1/2" in carbide, but perhaps I should get a set of TiN HSS too, if not for in-between sizes, but for practice. The TiN might be slicker than the carbide for aluminum.

With the execption of stainless it sounds like you really only need HSS. I don't know what you are meaning about running true with a milling cutter, they very rarely run true after the first time you dig into something. I could only see that being a problem if you were doing some sort of form tooling like a V or radius on a filltet. The fact of the matter is that mills get clogged and when side cutting you will get smaller chatter marks, this is more pronouced on smaller less rigid mills and with smaller end mills. As for sharpening end mills its not impossible to send them out to be resharpened, esp when you buy that 1" monster that you need for the odd off job. But I don't feel bad about throughing away a $5 1/4 endmill at work either. The person that does all my current lathe work has been doing my resharpening of HSS Tin coated mills for my personal stock to use at work. He charges me based upon how long it takes him, the most i have paid is $10 for a set of 5 and the edge was superior to the new edge.
Also don't shoot yourself in the foot when you buy endmills buy them by the dozen or half dozen. There will be something that will not go your way some day and you will either crash, or break end mills sometimes right in a row.

chris

[BrendaEM]

Perhaps cobalt would a happy medium, letting me work on harder materials, without the brittleness of carbide.

[under-dog]

Typically the more flutes the cutting tool has the better the finish but slower cutting.

The less flutes there are the faster the tool will cut and the less likely it will be to clog.

In essense the flutes somewhat ride the surface while cutting so the more flutes there are the more tool surface area the cutter will have to ride on.
Less chatter and therefore smoother cut.


This is a lesson for me not learned from milling but from years of hand carving with burs which works on the same principal. When hand carving I always start with a coarse but(less flutes) for the roughing out and do finish work with finishing burs (two to three times as many flutes). Without the rigidity of a mill behind it you hcan really see and feel how each reacts.

[robertbrenton]

I came across a comprehensive research paper at the following link which helped me understand the difference between cutter types, materials, no. of blades etc.

http://eprints.usq.edu.au/archive/00000102/

[BrendaEM]

I came across a comprehensive research paper at the following link which helped me understand the difference between cutter types, materials, no. of blades etc.

http://eprints.usq.edu.au/archive/00000102/

What a great resource, thanks.

[robertbrenton]

The document pretty much has everything a CNC hobbyist would want to know about the use of endmills from types, how to sharpen, cutting fluids, work materials, feed rate etc. Only bits which are of little use are pages 77 to 89 relating to the development of a multipurpose endmill.

I've opted for buying bulk lots of 10 of both 2 and 4 flute endmills in ball nose and standard. 2 flute for roughing, as suggested by other members, and 4 flute for finishing.